A police radar warning receiver employed in a motor vehicle provides visible and/or audible warnings when the vehicle is under police radar surveillance for possible speeding violations. A conventional radar receiver includes an antenna that receives incoming radar signals, internal circuitry that processes the received signals, and a visible light and/or audible alarm that indicates to the vehicle operator when police radar has been detected. Typically, these components of the radar receiver are located within a single housing mounted in the interior of the vehicle. Electrical power is supplied to the police radar receiver via a plug that can be inserted into the cigarette lighter receptacle of the vehicle.
To optimize the reception capability of the radar receiver antenna, such units may be mounted to the windshield as by suction cups, or clipped to the sun visor in a manner which provides an unobstructed signal path through the windshield to the antenna. However, for various reasons, mounting the radar receiver in this manner presents a number of disadvantages related to reception, convenience and theft prevention.
Firstly, under some conditions the windshield of a vehicle may be opaque to radar signals and adversely affect reception. For instance, when the exterior surface of the windshield is covered with ice or snow or not yet completely defrosted, transmission of radar through the windshield to the antenna can be impaired.
Moreover, some vehicles have windshields that incorporate transparent metallic coatings. These coatings are used to reduce solar heat gain within the vehicle, or to quickly de-ice the windshield (by using the resistive properties of the metallic film to heat the windshield by applying electrical power to the coating). Radar signals are greatly reduced or eliminated by these metallic coatings, and as such a radar detector mounted within a vehicle with such a windshield coating would have significantly reduced performance.
Secondly, a windshield mounted radar receiver and the electrical connecting cord extending from the cigarette lighter to a radar receiver may partially block or impair the driver's view through the windshield, or at the very least distract the driver.
Thirdly, mounting of the radar receiver adjacent the windshield places the device in full view of passersby and thus increases the risk of theft when the vehicle is parked. While the radar receiver can be disconnected from the cigarette lighter and removed from view prior to when the vehicle is left unattended, this is inconvenient to the driver.
For these and other reasons, "remote" radar receivers, or more precisely, radar receivers having their antennas mounted remote relative to the inside of the vehicle whereat the audible/visual alarm section is located, have become increasingly more popular. In "remote" radar receivers, the antenna portion of the receiver, which is mounted remotely from the separate audible/visual warning unit located in the interior of the vehicle, detects incoming radar signals. The received radar is then processed by the signal processing section, which is mounted proximate to the antenna. Following signal processing, a suitable warning signal is transmitted to the audible/visual warning section to provide the vehicle operator with an audible/visual warning that police radar has been received. Because the internally located warning section does not need to be mounted in such a manner as to receive signals through the windshield, and also because the antenna and processing circuitry are located remotely, the warning section can be reduced in size and easily mounted to, or under, the dashboard. This reduction in size promotes convenience in use and reduces the risk of theft. Aside from the fact that the smaller internal unit is more difficult to see from the outside of a vehicle, there is also reduced incentive for theft because the interior warning section will not work without the remote unit mounted inaccessibly under the hood.
Unfortunately, the advantages of increased convenience and reduced risk of theft come at the expense of optimum reception. For concealment reasons, the antenna section is typically mounted under the hood of the vehicle, and is aimed in a forward direction through the grill of the vehicle. Unfortunately, due to the different front end configurations of various types of vehicles, it may be extremely difficult to find a suitable location under the hood for mounting the remote antenna unit in a manner that aims the antenna down the road toward oncoming police radar signals. Even after the remote unit is mounted, the presence of electrically conductive grillwork in front of the antenna may interfere with optimum radar signal reception by the antenna.
It is thus an object of this invention to provide remote mounting of the antenna of a police radar warning receiver in a convenient manner which optimizes antenna concealment without sacrificing reception capability.